Interior walls typically are installed by use of flat, prefabricated boards which are assembled with the use of jointing material such as joint compounds, sealing coats, joint coats and/or joint-pointing coats. The prefabricated elements can be gypsum fiberboards, cement fiberboards, gypsum wallboards or plaster boards and the like. The flat, prefabricated boards typically include at least one sheet of lining paper, at least one outer layer of which has a visible outer face ready to be decorated. Generally, in the construction of interior walls, flat prefabricated elements, or drywall elements, are fastened to wall frames by, for example, nails or screws, and the joints taped or plastered with a jointing material. The prefabricated elements are assembled together, optionally with a jointing material and the joints are finished with a sealing coat, joint coat and/or joint-pointing coat, so as to obtain an overall visible outer surface which is relatively uniform or plane, including in the region of the joints.
After the interior assembly work has been completed, the preparation generally involves covering the overall surface obtained, i.e., the lining of the flat prefabricated elements plus the joints, with one or more layers of a paint or priming or finishing coat. The overall visible outer surface of the flat, prefabricated boards typically needs to be prepared, before receiving any surface decoration, such as by application of one or more layers of a film covering of the paint or lacquer type or a wallpaper. This preparation is necessitated especially by the shade or color differences existing between the visible outer surface of the flat prefabricated elements, for example plasterboards, and the visible outer surface of the joints.
The preparation operation represents an appreciable additional cost, for example in a complete process for the construction of a building. And, in some cases, it is still insufficient for obtaining an overall decorated surface of uniform appearance, particularly in view of the physico-mechanical differences prevailing between the joints and the flat prefabricated elements.